The use of intraocular lenses ("IOLs") has been highly developed in recent years, especially for implanting after the removal of cataracts, and such operations are now common medical procedures. In such procedures it is desirable to minimize the size of the incision which must be made to insert and position the IOL in the eye, in order to shorten the time required for healing and to minimize any chance of failure. Most implanting techniques have required that the incision in the eye be slightly wider than the diameter of the IOL to be implanted so that the lens can be inserted through the incision.
Recently, techniques have been developed for reducing the width of certain lenses by folding them prior to insertion, see V. L. Bohn, "Soft IOL Technology", Ocular Surgery News, Vol. 5, No. 5, Mar. 1, 1987, page 1. The use of a folded lens enables a smaller incision to be used than would otherwise be required; for example, a lens of 6.5 mm. diameter can, if folded, be inserted through an incision only 3.5 mm. wide.
My U.S. Pat. No. 4,769,034, previously referred to, discloses a foldable resilient lens which is retained in a folded configuration for implanting, by a retainer which is wrapped around the lens and temporarily held in place around the folded lens by ties. That enables the lens to be inserted through the same small incision which is used to remove a cataract from the eye. My co-pending application Ser. No. 213,325, previously referred to, discloses other means for retaining a folded lens, including a retainer which is integral with the lens itself, or alternatively sutures which extend through apertures in overlying parts of the folded lens. However, those techniques are relatively complicated in that they require securing a retainer around the lens, or suturing through the folded lens, or forming a retainer integrally with the lens.
My copending application Ser. No. 345,837, also previously referred to, discloses a lens which is held in the folded configuration by a retainer in the form of a pliable, severable endless band which extends around the lens. Once the lens has been inserted in the eye, the endless band is removed as by severing it lengthwise. However, placing the endless band around the folded lens will in practice typically be done at the point of production and requires a lens material with a long "memory" so that the lens will reopen to its original unfolded configuration and regain good optical properties even after having been folded for a protracted period. Some IOL materials, when folded, do not have a good "memory" of their original shape; they do not quickly return to their original design configuration. Further, the implanting technique requires the development of some skill on the part of the surgeon to release the band, otherwise the unfolding may be jerky and may cause stabilization problems.
Bartell U.S. Pat. No. 4,681,102 discloses a technique wherein an IOL is folded by rolling it up, and is then placed in a hollow injector or "shooter." A plunger pushes the IOL through an open end of the injector into the eye. It is difficult to insert the IOL into the injector at the point of surgery, and the lens design must accommodate the requirements of the injector. Moreover, the technique affords relatively poor control of the IOL during release; movement of the leaves of the lens is uncontrolled as they open from the rolled configuration. This raises a possibility that a part or leaf of the lens may strike the backside of the cornea and really damage the eye.
The Faulkner forceps, sold by Katena Corporation, are specially designed to compress and surround a lens for insertion into the eye. As in the shooter technique, a larger incision is required to accommodate the forceps-held lens. Generally that technique requires that the incision be somewhat wider, for example 4.5 mm rather than 3.5 mm. Further, after the lens has been inserted in the eye it is rather awkward to open the forceps jaws, and the surgeon has relatively poor control of the unfolding movement of the lens during this phase. Either the lens or the jaws of the forceps can strike and injure the cornea.
Thus there is a need for a technique to hold a lens in a folded configuration which (a) does not require a larger surgical incision than is used for cataract removal; (b) can quickly and easily be used at the time and place of use to fold and retain the lens; and (c) can easily be controlled to prevent possible injury to the cornea in implanting.